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- Author or Editor: Y. Erten x
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Abstract
Trace element levels in hair of individuals living in urban areas were determined by energy dispersive XRF. Two groups of subjects were investigated, the first group was assumed to be from a healthy environment, the other one was exposed to a high level of contamination due to working conditions. The results were compared to data reported in the literature. The concentrations of Ca, Fe, Cu, Zn and Pb in the scalp hair were determined and the correlation between hair trace element levels and environmental effects was discussed. The results given by the second group show that environmental exposure effects hair trace element levels which are related to body trace element concentrations.
Abstract
In this study, NaX synthetic zeolite was modified by following the conventional cation exchange method at 70°C. 82, 81, 79 and 48% of sodium were exchanged with Li+, K+, Ca2+ and Ce3+, respectively. Thermal analysis data obtained by TG/DSC was used to evaluate the dehydration behavior of the zeolites. The strongest interaction with water and the highest dehydration enthalpy (ΔH) value were found for Li-exchanged form and compared with the other forms. The temperature required for complete dehydration increased with decreasing cation size (cation size: K+>Ce3+>Ca2+>Na+>Li+). CO2 adsorption at 5 and 25°C was also studied and the virial model equation was used to analyze the experimental data to calculate the Henry’s law constant, K o and isosteric heat of adsorption at zero loading Q st. K o values decreased with increasing temperature and the highest Qst was obtained for K rich zeolite. It was observed that both dehydration and CO2 adsorption properties are related to cation introduced into zeolite structure.
